This invention relates to the field of battery chargers, and specifically to a battery charger with an integrated state of charge indicator on a visible outer surface of the battery charger.
In the power tool field, it is common to use different types of hand-held, cordless power tools to address the varied needs of the user of the power tools. It is also common to use power tools that operate on different voltages with different battery packs. The need to use different types of power tools and/or power tools of different voltages typically cause issues with battery chargers with multiple functions and recharging capabilities.
Certain power tools are powered by removable and rechargeable battery packs that require intermittent recharging. Having sufficient charge in a battery for a power tool allows a user to accomplish the task at hand. A battery pack can be attached to the power tool to provide power for operation of the tool. More than one battery pack can be used in conjunction with power tools. This allows one battery pack to charge while the other is being used. Depleted battery packs can be swapped out and recharged. Power tool users may not always be aware of the state of charge of each battery pack. Thus, a device to determine the charge state of a battery pack would be useful, particularly if in conjunction with the battery charger itself.
Although battery packs with a voltage indicator circuit are known, the chargers do not provide visible feedback to the user indicating the state of charge of multiple configurations of battery packs prior to entering the charge cycle.
U.S. Pat. No. 4,027,231, the circuitry of which is incorporated herein by reference, shows a circuit for use in a battery charger connected to multiple light emitting diodes (LEDs) to indicate the remaining useful charge of a battery.
U.S. Pat. No. 6,023,150, which is incorporated herein by reference, provides an estimate of remaining charge of a battery based on a variety of characteristics of the battery. The system also compensates for battery temperature.
U.S. Publication No. 2005/0134224 to Chuang, which is incorporated herein by reference, discloses a charger capable of displaying quantity of charge of a rechargeable battery. The charger has a display unit 16 can be a set of lights of multiple LEDs with each light distinguished by different colors or by labels allowing the user to judge how much the rechargeable battery is charged. After the rechargeable battery has finished charging, the display unit will provide multiple percentage levels for electricity quantity according to the display signal and then display the actual quantity of charge that has been charged to the rechargeable battery. The disclosure indicates that the charger can have a separate error detection light 14 that will flash to inform the user for a battery replacement or turning off the electric power.
Existing battery chargers may have a connection for a single device or provide a universal connector for individual connection to multiple types of devices. There is a need, however, for a charger that can receive multiple types of devices. In this regard, it would also be desirable to have a battery charger with an integrated state of charge indicator and fault indicator on a visible outer surface of the battery charger that can be viewed with various battery packs attached to the battery charger.